Dr. Alan Stern Answers Your Questions!

Article written: 27 Dec , 2011
Updated: 26 Apr , 2016

[/caption]Some of you may know, we recently launched a new “Ask” feature here at Universe Today. Our inaugural launch features Dr. Alan Stern, Principal Investigator for the New Horizons mission to Pluto and the Kuiper Belt. We collected your questions in our initial post and passed them along to Dr. Stern who graciously took the time to answer them.

Here are the questions picked by you, the readers, and Dr. Stern’s responses. We’d like to thank our readers for making this kick-off a success, as well as Dr. Stern for his participation.

1.) Many sci-fi authors have dreamed of putting some sort of telescope on the surface of Pluto to take advantage of the relative darkness and extreme cold encountered on this distant dwarf planet. How feasible would it be, judging from what we’re learning from the New Horizons expedition, to actually land a spacecraft, or a telescope, on Pluto’s surface? If such a telescope where deployed, how much more effective, if at all, could it be than an instrument like the JWST?

Alan Stern:“Space astronomy has revolutionized the way we look at the universe and is fundamental to modern astrophysics.” There are benefits to getting telescopes out of the atmosphere, and even benefits to getting out of Earth orbit, as in the case of Kepler and someday maybe JWST.

With regard to taking advantage of Pluto’s cold temperature – we’ve gotten really good at cooling down space telescopes. “There would be a benefit to placing a radio telescope on the far side of the Moon, but there’s no real practical reasons to place a telescope on Pluto—particularly given the cost of getting there, other than it being cool.”

2.) Kuiper objects differentiate strongly in color suggesting compositional or perhaps formation differences. Interestingly the color distribution correlates with the two different cold and hot Kuiper populations. Assuming the spectral analysis capability of New Horizon works for identifying the follow up Kuiper objects beyond Pluto-Charon, and given the putative possibility of choosing between several such targets, what type of target would the mission aim for? Would it try to cover as much diversity of objects as possible or is there a certain class of objects that could be important to concentrate on?

A.S: “We have to find Kuiper belt objects within our spacecraft’s fuel supply.” Stern elaborated, stating, “Predictions from our computer models tell us to expect to be able to have perhaps six possible candidates, to choose from, but so far we’ve just begun to search for these and though we’re finding KBOs, none we’ve found are yet are within the fuel supply.”

Stern also added, “Keep in mind our search for candidates isn’t easy – these are 27th magnitude objects which are roughly 50,000 times fainter than Pluto. What we’ll use to select between candidates once we have them are color, orbits, moons, rotational speeds – basically what combination of properties give us the most science for our fuel budget. The longer we wait after the Pluto flyby in July 2015 to make a decision, the more fuel will be consumed, so the “sweet spot” would be to have preliminary candidates in early 2015.”
(UT Note: New Horizons will perform its Pluto flyby in mid-2015 ).

3.) Given the limited funds available, Which do you recommend (Europa or Enceladus) as a suitable target for a mission in the 2025 time-frame in terms of value for money, scientific return, and practicality, and what kind of mission do you propose (lander vs. orbiter) ?

A.S: “Every scientist has their own judgment of what would make a good outer system flagship mission, or the best world to perform a series of missions that would equal a flagship mission.” Dr. Stern’s opinion is to explore Titan first, with Enceladus as a secondary target of that mission and Europa last, stating “Titan is the belle of the ball”, citing Titan’s active liquid cycle and thick atmosphere. Stern also added that he believes a mission to Titan would provide the most science per budget dollar.

4.) Four of the craft escaping the Solar System – Pioneers 10 & 11 and Voyagers 1 & 2 – have on board some sort of “message” to any possible extraterrestrials in the unlikely event they find it. Why was not some sort of message like that included on New Horizons, which may be the last (in our lifetimes) craft to also escape the Solar System?

A.S “There are several mementos onboard New Horizons, but no Voyager-like message.” Dr. Stern discussed a promise he made to his team that New Horizons would not be canceled and that he wanted his team focused on the science of the mission. Stern also pointed out that the process of deciding what to place on the Voyager plaques became mired in political correctness, (should the humans have been clothed? What cultures and races should be represented, etc.)

By separating the “icing from the cake”. Stern and his team have been able to concentrate on their main objective—to execute the New Horizons mission for about twenty cents on the dollar, as compared to the Voyager missions. Stern concluded with, “I’m proud that we got this done and that New Horizons is operating perfectly now way out there between Uranus and Neptune and flying almost a million kilometers per day toward the Pluto system.”

5.) Are any present or foreseeable technologies being considered for exploring the depths of our four “gas giant” planets?

A.S “There are no serious proposals to put a probe into one of the giant planets now, or even any call for such in the recent decadal survey for planetary missions. Keep in mind, though, that the Juno mission (now en route to Jupiter ) will use powerful remote sensing techniques to probe Jupiter from orbit around it to greater depths than the Galileo probe (which actually entered Jupiter’s atmosphere).”

6.) Why was it considered “urgent” to get to Pluto before the atmosphere refroze?

A.S “We have three “Group 1″ objectives for New Horizons. Map the surface, map the composition, and assay the atmosphere.” Stern referred to the objectives as a “three legged stool” in that no one objective could be omitted and still justify the mission, adding “so we need to accomplish that.. we need to get there before the atmosphere collapses”. Stern also referred to Pluto’s atmosphere as “very different from any other planet yet studied”, hence its inclusion as one of the three “Group 1” objectives.

7.) The Dawn mission to Vesta has shown us a body that was much less round than expected. Do you think it is possible that New Horizons will surprise us about Pluto, to the same degree? Please compare the expectations of the New Horizons fly by, to the early images of Vesta from Dawn.

A.S “With New Horizons being the first mission to Pluto, we will be surprised—after all, we’re always surprised on first reconnaissance flybys”. Stern added, “With Mariner 10, we discovered Mercury was all core, with Voyager we discovered volcanos and geysers across the outer solar system, and of course we were surprised when craters and river valleys were discovered by early Mars probes.”

Regarding Pluto, Stern stated “Pluto is the first discovered and soon to be reconnoitered of the most plentiful class of planets, while I’m not big on making predictions, I will say that what we will find will certainly be, well, wonderful.”

9.) Can new horizons now take more detailed photos of Pluto than HST? If not, when does it get close enough?

A.S “Great question! We actually thought about that a lot when designing New Horizons. One of our instruments, LORRI (Long-Range Reconnaissance Imager – http://pluto.jhuapl.edu/spacecraft/sciencePay.html) will provide us with views better than HST around April of 2015, and we expect to have about twenty weeks (10 weeks before, 10 weeks after the Pluto flyby) when we “own” the Pluto system — and I can guarantee the best images we hope to make should be as good as Landsat images of Earth!”

That wraps up our interview with Dr. Alan Stern. Once again, we at Universe Today would like to thank Dr. Stern for his gracious participation. If you’d like to learn more about the New Horizons mission to Pluto and The Kuiper Belt, visit: http://pluto.jhuapl.edu/index.php

Next month, we’ll be having an “Ask an Astronaut” feature with Mike Fossum, Commander of Expedition 29 on the International Space Station. Stay tuned!


84 Responses

  1. HeadAroundU says

    “class of planets”

    Oh, you certainly mean a class of dwarf planets, right? :DDD Because, classes of planets would be, terrestrial, ice giants and gass giants. 😀

    • laurele says

      Dwarf planets are a subclass of planets, in spite of what four percent of the IAU might think. Stern is the person who first coined the term “dwarf planet,” back in 1991, and his intention was to create a new class of planets, small bodies large enough to be rounded by their own gravity but not large enough to gravitationally dominate their orbits.

      UT, Stern was a great choice for your first “Ask” column!

      • Torbjörn Larsson says

        Wrong. The IAU definition of planets, which indeed excludes dwarfs, is backed by, surprise, surprise, the IAU. How else could it be?

      • laurele says

        By the IAU, you mean the IAU leadership, namely the executive committee and secretariat. There are plenty of individual members who do not support the decision. I’ve met a lot of them. A group asked the IAU leadership to reopen the debate at its 2009 Genera Assembly, and the leadership refused, leading the entire group to boycott the GA. Then there are many professional astronomers who are not IAU members who also do not support the IAU decision. See this petition of professional astronomers led by Stern: http://www.ipetitions.com/petition/planetprotest/

      • Steven C. Raine says

        Well said, Laurele. The IAU got it wrong at the last minute when their original definition would have been better and other even better alternative definitions also exist. There are many logical and consistency problems with the IAU definition and it begs the question of what woudl happen if an Earth or even Jupiter sized world is found orbiting in the Oort cloud – by definition making it NOT a planet despite the fact that it would unquestionably be one if located closer in. Then too, we call our star a yellow dwarf star and do not limit stellar objects based on their size or commonality so the same should apply forplanets too – and the IAU definition excludes all the exoplanets and thus is already terminally out-of-date and in need of correction because everyone is quite happy to call them planets. The IAU got it badly wrong in 2006 and the sooner they correct their error (which I can’t see lasting) the better for them and astronomy generally.

      • HeadAroundU says

        There are no problems with the definition, you just don’t get it because you are not smart enough.

        What would happen if you found another earth or Jupiter there? Find it first and then we can talk.

        You can’t mix classification of stars and planets. It’s a different system and it’s bound to evolve a different taxonomy.

        Exoplanets are not a problem yet and I don’t think they will be because once a system gets stable I think that the same rules will apply. We could simply exclude unstable systems. Nothing’s out of date, don’t lie.

        Planets/exoplanets, both things can be easily fixed in the current definition. It’s basically interchangeable.

        The bigger problem I see is that the rest of IAU are bigots and it’s a shame that scientists can’t use their brain.

      • laurele says

        Actually, there is a common thread in the classification systems for stars and planets. Both are based on mass. A planet is an object massive enough to be rounded by its own gravity, and a star is an object massive enough to be self-luminous through nuclear fusion.

        Please explain how you apply the same IAU rules to exoplanets when most of those discovered do not fit that definition (i.e. have overlapping or eccentric orbits) and the IAU itself has stated the definition does not apply to exoplanets?

        If we find another Earth or Jupiter, we may very well have to revise most of what we know about planets. It makes no sense to set ironclad definitions when we still know so little about what is out there.

      • Anonymous says

        Again all this is, is a rehash of a rehash of what you’ve already said before. (it’s called parroting — meaning repeat mechanically. Don’t you have anything new to add here?

        Funny isn’t it. Even your notions and definitions are quite clearly nonsensical. Worse they simply contradict the arguments and statements already said by you in this storyline (let alone elsewhere.

        It takes one point to kill your argument. I.e. You say here; “A planet is an object massive enough to be rounded by its own gravity,…” Eh? Would that assume that the constituents making up the planet was liquified at one stage? How about how planets are formed by small planetesimal or protoplanets? Are these planets too?

        Here your childish responses are exactly that; childish. The problem is NO DEFINITION here is clear cut nor infallible. The IAU morphological definition of a “planet” is a basic broad-based compromise satisfying the widest practicality of the definition.

        It is really funny you know. You are totally unable to give any realistic alternative definition here, but you can only bitterly bemoan anything and anything under the sun (sic) about the current IAU one.

        Your only definition, in fact is on the proviso, that ANY definition must include Pluto. (And that too is is illogical and unscientific.)

        Bottom line is that this makes you as silly or sillier than the complaints you are alleging to have occurred!


        Amen to that!

      • laurele says

        There are not only eight planets in our solar system no matter how many times you repeat that there are.

        Even the IAU acknowledges the importance of an object attaining hydrostatic equilibrium, meaning being rounded by its own gravity. This happens via accretion, for both rocky and gaseous objects.

        Many planets do have a liquid core because of geological differentiation. The heavier elements sank to the bottom during planet formation while the lighter elements formed the planet’s outer layers.

        You’re putting words in my mouth. I never said any definition must include Pluto. I do say that any definition must be broad and include all objects in hydrostatic equilibrium, including dwarf planets, as a subclass of planets.

      • Anonymous says

        “There are not only eight planets in our solar system no matter how many times you repeat that there are.”

        Now saying THAT just proves beyond any doubt that you are indeed quite delusional!
        (As I’ve said all along)

        As for; “I never said any definition must include Pluto.”

        Oh yes you did!! It is been the whole monumental crux of your sickening emotive language and obvious bias in everything you have written is to that sole purpose of desperately wanting to restoring Pluto to planet status.

        Towards “definitions” you’d do anything, say anything, just to get Pluto reinstated.

        I think your ideas are so twisted you’ve forgotten what you’ve been arguing about.

        The only way you can wriggle out of this here, is to admit you are just plain stone-motherless wrong.

        Game, Set and Match! methinks…

      • laurele says

        Nice try, but no cigar. I bet you haven’t visited a single site I’ve referenced, where PhDs in planetary science make the same arguments I do for a geophysical planet definition.

        “Sickening emotive language???” Who are you, and why do my comments bother you so much? If you really thought I was that far off base, you wouldn’t even be reading them!

      • Anonymous says

        I couldn’t care less about you references. Your bias makes them irrelevant!

      • HeadAroundU says

        A common thread doesn’t make it identical.

        Like I said, you could exclude unstable systems. We will see if planets and exoplanets will be separate. It’s too soon to tell.

        Find it and we can talk. It makes sense, it’s a reality.

      • laurele says

        What factors distinguish stable from unstable systems, and how can we determine these given the limited amout of data we have about exoplanets? We haven’t even seen one complete extrasolar system with all its planets yet.

      • Torbjörn Larsson says

        How is the new definition “badly wrong” and in “error” (or a “mistake”), when it is:

        1) taken according to our best working method for societal decisions

        2) is better than the preceding threatening chaos, that prompted the change


        You keep using those words. I do not think they mean what you think they mean.

        And no, you don’t reverse even small mistakes when the change is arduous. Remember that IAU prepped its decisions for many years, it was not a hasty one.

        Fortunately they took a good enough decision: it works.

      • laurele says

        If you watch the video here http://www.iau.org/public_press/videos/detail/iau2006session2/ you will see that the session in which the vote was taken was rushed in order to come up with any outcome and that objections by astronomers who disagreed with the proposal were completely ignored. The session is more of a circus than a scientific discussion. There were even more outrageous comments made in other sessions, such as the remark by one astronomer that if Pluto were kept as a planet, his life work would be ruined.

        This session was in no way “the best working method” available. Just the fact that 96 percent of IAU members were excluded is enough to subject it to revision. Why, even now, does the IAU not allow electronic voting? It is a decision on which there is no consensus among astronomers more than five years later, which alone says something about its scientific merit. Hundreds of professional astronomers signed a petition opposing this decision, as can be seen here:

        Chaos and indecision are better than having an overly narrow and politically determined decision imposed by fiat, a tactic appropriate for churches, not scientific groups.

        The IAU may have spent years working on this, but in a few days, a small minority of members hijacked the process, threw out years of work, and imposed their own resolution instead. The disrespect for the IAU’s years of work came from within the IAU itself. This particular vote was done in a hasty manner; the proper procedure when the first resolution was voted down would have been to put off a decision until the next General Assembly.

        If you want scientific credibility, you DO reverse decisions that do not reflect the reality shown by the data and cause far more problems than they solve. It was not a good decision, and it was not progress. In fact, it was based on an erroneous notion, namely that Eris is larger than Pluto, which it is not. If you’re bored by the discussion, there is a simple answer–don’t read it, and don’t participate in it.

      • Anonymous says

        Stupid is as stupid does. There are so many holes in this reply, I frankly don’t know where to start.
        The only thing erroneous here is your very scrambled emotive thought processes. Clearly you cannot see other points of view or place yourself in the other person’s shoes – which, as we know, most have usually discarded in their early formative or teenage years.
        The real question for us all here is why you are behaving or want to behave in this crazy way? Is this some attention seeking strategy or plainly issues with authority? One can only wonder if this posturing is merely disingenuous prattling of quite gratuitous and ill-informed opinions against meaningless trivialities of quite minor importance.

        I think that science credibility is not the problem here. It seems to be that your own credibility is what is somewhat lacking.

      • laurele says

        Please address the specifics of why my arguments are “stupid.” I do recognize that this is an ongoing debate with two legitimate sides, and I respect opponets who present their arguments in a logical way, addressing the issues. You haven’t said a single word about astronomy. Personal attacks are the resort of those who are losing the debate.

      • Anonymous says

        Easy. We heard all this claptrap from you before, so why go over old ground?
        As for not saying a single word about astronomy might indicate just how twisted your irrationality really is. You are using ridiculous emotive tactics and then pretending this is on some scientific level. Without doubt this proves your crazy notions are both childish and irrelevant.
        Really how can you debate arguments in a logical way when the opponent is so biassed, delusional and pigheadedly so single-minded? You can’t.

      • laurele says

        I acknowledged there are two legitimate sides to this debate. How is that irrational?

        Now you’re blaming me for the fact that you cannot write a single sentence pertaining to astronomy? Please. I am not responsible for your poor debating skills.

      • Anonymous says

        I’m not responsible for your gibberish!

      • Torbjörn Larsson says

        In your first comment you tried to imply that IAU wasn’t using a democratic procedure of such organizations.

        Now you are claiming that democracy sux. Well, it does, but it sux less than the alternatives. Which is why it is generally used and has put a damper on sundry conflicts. (See Rosling’s world statistics.)

      • laurele says

        Only four percent of the IAU voted because the IAU does not allow electronic or absentee voting, meaning unless a member was in a particular room on a particular day, he or she could not vote. The vote was conducted in violation of the IAU’s own bylaws, which state that a resolution cannot be put on the General Assembly floor without first being approved by the appropriate IAU committee. Many participants left the General Assembly early expecting the IAU to vote on the resolution its own committee recommended, which included Ceres, Pluto, and Eris as planets. They had no idea the IAU would violate its bylaws and throw in a different resolution for a vote at the last minute–meaning those who left early were essentially deceived. Dr. Owen Gingerich, chair of the IAU Planet Definition Committee, has publicly stated that had he known this would happen, he would have canceled his plans to leave and stayed until the end of the conferences.

        Voting is not necessarily appropriate in science. No one voted on gravity or relativity–these things were tested, challenged, and proven over time. Why isn’t the IAU voting on a definition for dark matter? Facts are not determined by the vote of an “authoritative body,” but by the data itself. We are only now learning about the wide variety of planets in the universe, meaning it is way too soon to create a narrow definition.

      • Anonymous says

        Blah blah blah…. Those like Gingerich just showed how absolutely childish and narrow-minded he and others were.
        Boo Hoo. “Crying over spilt milk” and then berating those for taking a very obvious logical and need decision, looks utterly disgusting and is clearly a misrepresentation of the whole truth.
        If I was among IAU leadership, I’d immediately censure all these misanthropes publicly stating demonstrably as wilful troublemakers and then ban all of them from participating in any future IAU meetings.
        As for your sordid slights against the IAU here, I’d be careful in what you say. Sallying such international institutions is tantamount to creating deliberate disharmony among all nations. Undesirables like you showing such lack of judgement and irresponsibility might come back and bite you.
        Really. Ostracism as an option should be placed on the IAU by-laws, IMO, and ignominious twits like you should start to behave properly instead of just drumming up emotive discontent. You should know better.

      • laurele says

        I challenge you to send this statement to Dr. Gingerich or to Dr. Stern. I don’t think either would appreciate it and not because of their positions on Pluto.

        If the IAU did what you suggest, that would only hurt their credibility and hasten the formation of alternative astronomical groups.

        Your suggestions are very troublesome because such tactics equate to tyranny and could be used against scientists who think differently. The result would be more Galileo trials, which don’t belong in an open marketplace of ideas.

        My statements about the IAU are not “sordid slights.” They are condemnations of procedures that were conducted inappropriately. The IAU leadership knows who I am, and surprise–they even let me write an article for their 2009 General Assembly newspaper.

        Disharmony among nations? Are you saying this debate will cause some type of war? Now who is being overly dramatic?

      • Anonymous says

        Sorry, you are fooling absolutely no one here. Half truths and innuendos is no basis to debate anything.
        Showing complete disrespect about the IAU shows you have little understanding about democratic processes at work. Your utter arrogance in the end will be your undoing. You will deserve everything coming your way.

      • laurele says

        “Your utter arrogance in the end will be your undoing.”

        Quoting Star Wars now?

        What is your interest in Pluto? You’ve written a lot of BS about me, but very little about Pluto itself. How about sticking to astronomy?

      • Anonymous says

        How about dropping all this the obfuscation?

      • Anonymous says

        Oh dear, not this same old broken record that you rabbit on about verbatim. Boycotting! (Giggle) More like whining and dummy spitting just like a four-year-old child who isn’t getting her own way just makes your arguments even weaker and more pathetic.
        I frankly hope they deregister these supposed ‘professional’ astronomical astronomers for acting like belligerent misanthropes! Clearly the IAU here has made the correct decision.

        KEEP PLUTO DEMOTED! I’d say!

      • laurele says

        I didn’t organize that boycott; a bunch of astronomy PhDs did in response to a dogmatic refusal to reopen an ongoing debate. Are you saying the IAU should excommunicate all members who do not agree with their decision for heresy? That sounds a lot like religion rather than science, which is why they will never do such a thing. The IAU has even admitted they have no authority to impose their definitions on the world. This is something the media has failed to grasp.

        Why are you so bothered by viewpoints that dissent from yours? Are you looking for science to be a dictatorship?

      • Anonymous says

        Scientists act like scientists. It is not some emotive disingenuous or religious claptrap like you are mentioning here. (I haven’t even till now mention religion.) Simple. If you cannot behave or think like scientists should, then you should not be a representative of that science!!!!!!!

        Scientists in this matter have acted in accordance by science and NOT by the divisive, quite irrational or emotional discourse you are simply displaying here.

        Also it is 110% true is that YOU HAVE NO AUTHORITY TO IMPOSE DEFINITIONS EITHER?

        I’d Trust the IAU More Than You!

        The fool stands naked and exposed!

        You are clearly an actress whose method of overacting does you more disservice than you realise. Most of us can easily see you need a reality check, and frankly, need to be booed of the stage!

      • laurele says

        No one has any authority to impose definitions. We learn the facts by observation and experimentation. Interpretation is different. Several scientists can look at the same facts and see different things. That is what happens with the dynamical and geophysical planet definitions.

        Did you watch the video of the IAU proceedings? The fact is, many astronomers who took part in these proceedings did NOT act like scientists. That’s why Dr. Stern called the decision “an embarrassment to astronomy” and “bad science that would never pass peer review.”

        Are you saying that anyone who disagrees with the IAU decision is a fool? That would make a lot of scientists fools, and I don’t think that is your intention.

      • Anonymous says

        “Are you saying that anyone who disagrees with the IAU decision is a fool?”

        No, but in your case yes! You are so darn biassed in your opinion you can’t tell the forest from the trees. Plain logic, common sense, manners, respecting due process, etc. etc. mean nothing to you.

        Your statements here are clearly delusional, and whose opinion here is meaningless!

      • laurele says

        Please visit the sites to which I’ve referred or better yet, contact Dr. Stern himself. This is not about individuals; it’s about different ways of viewing the solar system.

      • Anonymous says

        It is about DELUDING yourself to an imaginary solar system that is in your own twisted mind.

      • Torbjörn Larsson says

        Wrong. The IAU definition of planets, which indeed excludes dwarfs, is backed by, surprise, surprise, the IAU. How else could it be?

      • HeadAroundU says

        Good morning, it’s not 1991 anymore. Conform to 2012, please. Or at least act because you are an actress.

      • laurele says

        That would mean going from a solar system with 8 or 9 planets to one of several hundred. The latter is today’s reality.

        The IAU distorted Stern’s term in crafting its resolution, which was disingenuous and does not reflect Stern’s intention in creating the term.

      • Anonymous says


        More like emotional emotive claptrap again by a foolish woman (yet again.) Boo!

      • laurele says

        It was disingenuous because the IAU members who left before the last day were misled into thinking that the resolution approved by the IAU’s own Planet Definition Committee would be the one put to the floor of the General Assembly rather than a different resolution.

      • Anonymous says

        Aw please! Are you really that naive?

        You don’t even realise they put blinkers on horses so they actually run in the right direction!

        Clearly the “Planet Definition Committee” makes recommendations. The “General Assembly” can ratify or modify any recommendation as the main resolution.

        I think you have no absolutely no idea of how democratic committee systems have to work to enact Resolutions. I.e In this case, the “Planet Definition Committee”, can not ratify anything without general consent.

      • laurele says

        “Clearly the “Planet Definition Committee” makes recommendations. The “General Assembly” can ratify or modify any recommendation as the main resolution.”

        Every organization has its own set of bylaws. In the case of the IAU, their bylaws specifically state that a resolution has to be approved by the appropriate committee before being put to the General Assembly for the vote. Instead, knowing they had no time to do this in the last days of the General Assembly, the authors of this resolution decided to ignore the IAU’s bylaws altogether.

      • Anonymous says

        Aw please! Now you are making it up as you go along…
        I’d advise that you should never run for public office, as you clearly have no idea what you are saying! Really.

      • laurele says

        I suggest you read the IAU bylaws in detail.

      • Anonymous says

        I’d advise you to start speaking the truth without the hype.

      • HeadAroundU says

        You are deluded. We have 8 planets now. Please, visit your doctor.

        What is he? Some kind of god? And everything he says must become the truth? Sounds like a religion.

      • laurele says

        Stern is the Principal Investigator of New Horizons. No, he is not a god, and no one’s word should blindly be accepted as truth. He does, however, make very sound arguments for a geophysical planet definition and for the case that we do NOT have only eight planets.

    • laurele says

      No, classes of planets include terrestrials, gas giants, ice giants, dwarf planets, and any other type yet to be discovered (possibly hot Jupiters and super Earths among them).

  2. HeadAroundU says

    “class of planets”

    Oh, you certainly mean a class of dwarf planets, right? :DDD Because, classes of planets would be, terrestrial, ice giants and gass giants. 😀

  3. Torbjörn Larsson says

    I would like to thank Dr. Stern for his thorough answers. My own Q is in there, and it has a satisfying answer in that science will be maximized so there is no specific hypotheses pursued under the project. Which is, I assume, the best strategy regards the outcome for the whole science community.

  4. Torbjörn Larsson says

    I would like to thank Dr. Stern for his thorough answers. My own Q is in there, and it has a satisfying answer in that science will be maximized so there is no specific hypotheses pursued under the project. Which is, I assume, the best strategy regards the outcome for the whole science community.

  5. Joel N says

    Thanks for the informative answer, Doc. I’ll watch developments along those lines.

  6. Anonymous says

    Very good of Dr. Stern to take the time to answer these questions and his answers say to me he is the right man for the job, I look forward to 2015.

  7. Steven C. Raine says

    Can’t wait til 2015 and the images from New Horizons of Pluto & Charon. I’d love to see a mission to land on or atleats orbit this little world and also one (or two or three ..) that could do what ‘Dawn’ does in the asteroid belt and move from say, Pluto on to Haumea and Sedna and other ice dwarfs.

    Pluto really is a remarkable, wonderful little world and still my favourite planet!

    Incidentally, the way I look at things the IAU made a terrible mistake in demoting Pluto and claiming that dwarf planets – unlike dwarf stars – don’t count somehow as “proper” planets. We have three main types of planet in our solar system – the rocky, the gassy and the icy! Just because a planet is small and belongs to the most common type of planet (ice dwarf as opposed to rock dwarf or gas giant) shouldn’t disqualify it from planetary status. I believe a much better definition would be that a planet is an astronomical body that :

    1) has sufficient mass to be rounded or ellipsoidal (ie. in hydrostatic equilibrium) thus not an asteroid or comet,

    2) has never been self-luminous by internal nuclear fusion thus is not a star, brown dwarf or stellar remnant &

    3) does not directly orbit another planet and thus is NOT a moon.

    I believe that is a simpler, more inclusive, clearer and superior definition and really hope the IAU revisits this issue and corrects their mistake ASAP.

    • HeadAroundU says

      You know what’s simple? To have 8 planets. We really don’t need 200 planets.

      • laurele says

        How is limiting the number of planets in the solar system scientific?

        It would be simple to limit the number of Jupiter’s moons to four. Why aren’t you advocating that?

      • Anonymous says

        What a ridiculous circular argument. Clearly it isn’t, or is it?
        Yet again, just more irrelevant rhetorical nonsense using obfuscation just to avoid your own bizarre and illegitimate agenda.
        Plainly bitterness just because no one will listen or agree with you exposes your obvious folly!

      • laurele says

        “Bizarre and illegitimate agenda?” Really? You sound like a conspiracy theorist. The solar system has whatever number of planets it has, just like the universe has billions of galaxies which each have billions of stars. If “no one is listening,” why are you here, and why do you care so much what I say?

      • Anonymous says

        Oh dear. Another series of self-obsessed delusions. All i care about is the people like you don’t get away with the deception. Too many are happy to treat science and scientific authority with utter contempt, pretending it is all some kind of Bohemian expression or social popularity contest.
        The real offence here is your ridiculous banal arguments and disinterest in the facts. “Bizarre and illegitimate agenda” about sums up your position here. (Only a fool would have the audacity to consider this “conspiracy theorist” when she is actually the one acting like conspiracy theorist.)

      • laurele says

        Appealing to authority is a logical fallacy, as are ad hominem attacks. Just because a person or group of people in positions of authority say something doesn’t make it true. Why don’t you listen to the audio transcripts of the 2008 Great Planet Debate, held in response to the IAU decision? They can be found here:
        Both sides of the debate were represented here, and everyone was friendly. Another suggestion–contact Dr. Stern and ask him.

      • Anonymous says

        Even more foolish nonsense…
        Logical fallacies, ad hominem attacks? These are just piffle against being dead wrong – which you continue to serve in spades. Give up before you look even more silly…

      • laurele says

        Sorry, I’m not giving up on Planet Pluto just because you want me too. But I may give up on you if you don’t start making posts about astronomy instead of personal attacks.

      • Anonymous says

        I’m tell you to drop it because it is making yourself look foolish. Such bias in what you write is not doing you any favours!

      • laurele says

        And I should listen to you–why??? You haven’t made a single credible argument. Sorry, but you don’t get to tell me what to do.

      • Anonymous says

        Nor you…

      • HeadAroundU says

        How is expanding the number of planets in the solar system scientific?

        I haven’t looked into it. I think they are separated into groups. If it becomes a problem, I’ll make an opinion on it.

      • laurele says

        What is scientific is accepting and including the number of planets the solar system has, even if that number is several hundred.

      • HeadAroundU says

        So you don’t respect history? Taking away one object is more sensitive than adding 200. Are you insensitive?

    • Torbjörn Larsson says

      How is it a mistake?

      – The science stays the same.

      – The naming convention stays the same for the old part. While it becomes possible to absorb thousands of bodies in other populations like Kuiper’s and Oort’s without having to name each and every one with a more rigid system. This is why the change was proposed and introduced.

      • laurele says

        It’s a mistake because “absorbing thousands of objects” in the Kuiper Belt and Oort Cloud blurs the distinction between the majority of objects, which are tiny and shaped only by chemical bondss, and those objects large enough to have attained hydrostatic equilibrium, meaning they are rounded by their own gravity. The latter are much more akin to planets than to asteroids or comets–they have geology and weather and are geologically differentiated into core, mantle, and crust, just like Earth is. We don’t object to having billions of stars or billions of galaxies, so why object to billions of planets? Objects cannot be defined solely by where they are while completely excluding what they are. That is what the IAU definition does, and that is why it is bad science.

  8. Member
    Anonymous says

    I do hope the UT staff start deleting these Pluto arguments from the comment sections of utterly unrelated articles. Commenters on both sides just cannot seem to restrain themselves.

    • Torbjörn Larsson says

      I’ll admit that factual errors on science blogs pokes my SIWOTI syndrome more than elsewhere.

      If it all goes, I am happy with that.

      • Member
        Anonymous says

        Disqus has a list of accepted html here. I found it a week ago when desperately wanting to know how people were making blockquotes 🙂

        Yes, a big shame about the lack of superscripts. I would suggest pestering them through their general enquiries email address. I reckon with a little persuasion, they’ll implement it. Their email is [email protected] (it’s not easy to find on their website)

      • Member
        IVAN3MAN_AT_LARGE says

        Currently, media feature option on Disqus are disabled on the UT site.

    • laurele says

      Cutting off debate is not conducive to progress or to the advance of science. If one has to stifle debate, something is inherently wrong with one’s argument.

      • Member
        Anonymous says

        That doesn’t mean the debate is sensible to have in every discussion. If this were an article about cats it wouldn’t be relevant, and it’s not relevant in an article that just mentions Pluto either. If it were an article about planet classification, then by all means argue away.

        Science isn’t advanced by comments on a news website, so science wouldn’t be retarded by any censorship of discussion.

      • laurele says

        Censorship is never a good idea.

      • Anonymous says

        In your case, it probably is….

      • laurele says

        I get that you don’t want to hear any view that differs from your own.

      • Anonymous says

        More obfuscation and delusion….
        I’d happily hear or read anything on the subject, but I strongly object to motives and tactics that are aimed to deceive or evade the actual facts.
        If you’d both to place a balanced argument things might be different. After all, you the one poisoning the well here not me.

  9. Anonymous says

    Just an addendum to the “exploring the depths.” There is a serious proposal to send a deep probe into Saturn’s atmosphere, and is a potential New Frontiers mission in the next call, whenever that may be. For the near future, if all goes well, Cassini will drop its periapse inside the main rings in 2016 or 2017, and perform a similar (but not identical) set of measurements to Juno at Jupiter. Should be neat!

  10. Member

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